Enantiomers eutomer

It is common to call the most active enantiomer eutomer and the less active one distomer. The ratio of the pharmacological activity of these are called the eudismic ratio (ER) and Pfeiffer s mle states that the lower the effective dose of a drug the greater the difference in the pharmacological effect of the optical isomers . When two enantiometic... 

As can be seen from Figure 2, the (/ )-enantiomers (eutomers) of the silanols 3 and 7 show a significantly higher affinity for muscarinic M2 and M3 receptors than the corresponding (S)-antipodes (distomers). To the best of our knowledge, this is the first example of a biological discrimination between enantiomeric silicon compounds, with the silicon atom as the center of chirality. The stereoselectivity indices SI [SI = Kn S)/Kd(R) for sila-procyclidine (3) are 1.8 (M2) and 4.1 (M3), respectively. For sila-tricyclamol iodide... 

Dobutamine is structurally similar to dopamine but does not bind to dopamine receptors and is not associated with norepinephrine release from neurons. The drug exists as a racemic mixture, both isomers possesses p adrenergic effects, with the (+) enantiomer (eutomer) being 10 times more potent than the (-) enantiomer (distomer). Furthermore, the eutomer is a potent a adrenergic antagonist while the distomer is a potent... 

In the second scenario, target products and impurities are present in similar amounts. The separation of racemic mixtures exemplifies this scenario. The problem of racemic mixture formation often occurs during chemical synthesis, where 50% of the mixture consists of the wanted enantiomer (eutomer) and 50% is the unwanted enantiomer (distomer). In this case competitive adsorption and the elution order of the enantiomers are of special interest (Section 4.3.4). 

Stereoselectivity was defined by Rauws as follows Stereoselectivity is the extent to which an enzyme or other macromolecule, or macromolecular structure (antibody or receptor) exhibits affinity towards one molecule of a pair of isomers in comparison with and in contrast to the other isomer. . Lehmann has expressed this in a mathematical form the ratio of activity of the better fitting enantiomer (eutomer greek, eu = good), to that of the less fitting enantiomer (distomer greek, dys = bad) is defined eud-ismic ratio. From this an eudismic affinity quotient can be derived (Table 26.3). 

Terpenes. Permeability of the S enantiomer (eutomer) of propranolol was compared to that of racemic propranolol with or without terpene enhancers across guinea pig abdominal skin [69]. Stereoselective permeation of S-propranolol was observed in the presence of menthol, a permeation enhancer, where an increase in membrane permeability coeffident of the eutomer was observed, compared to that of the racemate. The enhancement factors were 2.12 and 0.85 for S enantiomer and racemate, respectively. Lag times were also reduced considerably compared to the control (without enhancer) [70,71]. 

Members of the 2-APA class of NSAIDs have the potential for in vivo enantiomeric inversion, whereby the R-enantiomer (distomer) may be inverted to the active antipode, the S-enantiomer (eutomer). The S-enantiomer... 

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